EAST KALIMANTAN, Indonesia -- Massive fires that ravaged Indonesia's vast tropical rain forests over the last decade are remaking one of the richest biological landscapes on the planet.
The fires have reshaped the habitat on much of Borneo, the world's third-largest island -- changing factors from the height of the forest canopy to water levels in the rivers and humidity in the air. That, in turn, is affecting which animals rebound and which ones peter out.
Among those species that appear to be thriving despite ongoing threats are dozens of species of bats that nest in the cave systems on the southern part of the island, an area known as Kalimantan, and feed on insects in the forest at night. But other small mammals, along with a multitude of bird and plant species, have yet to recover from massive destruction caused by the 1997-98 fires, considered the largest in recorded history.
When fire occurs, "the generalists survive," said Leo Salas, a Venezuelan biologist working here with the Nature Conservancy, a Washington-based environmental group. "The specialists don't."
The cave-dwelling bats are prospering in and around many of the new "secondary" forests that have regrown even in areas that burned two or three times, based on early results from a month-long biological survey by the Conservancy of sites on the Sangkulirang Peninsula. Many of them are flexible about where to roost, and they eat a variety of mosquito-size insects.
"I've taken more species [of bats] in this project then I have ever," said Matt Struebig, a conservation biologist at the University of London, who has been collecting and categorizing bats in Southeast Asia's biological hot spots for three years. Last summer, Struebig found 22 species at one site alone during a week of trapping, capturing several species not previously known to exist in the area.
Struebig thinks that caves protected certain species of bats from the fires, even as species that live in the forest declined.
"These are among the most biologically active caves I've ever seen," said Cyndie Walck, a geomorphologist with the California State Parks System.
Other scientists taking part in the biological survey in harder-hit areas had less encouraging findings.
The effects of the fires on some insect species, according to Louis Deharveng, a French biologist with the Museum of Natural History in Paris, were "devastating."
Luckily for the bats, the high and inaccessible limestone caves that dot the landscape here often are out of reach of loggers.
The porous, cave-pocked limestone cliffs -- a kind of terrain known as a karst system -- formed from coral reefs that lay under the sea 2 million to 3 million years ago. The reefs were compressed into limestone through continental drift, and now appear as jagged white rock formations puncturing the flat, green landscape. Over time, water has picked up carbon from the soil, eventually forming calcium carbonate, which slowly dissolves the rock to carve out caves and sinkholes.
"Karst areas are often last refuges for fauna," said Jaap Vermuelen, a Dutch scientist who works at the botanical garden in Singapore. "All the surrounding lands are heavily used [and] logged. But limestone caves, because of their inaccessibility -- they're still there."
Some of the biggest caves are far from any village and can be reached only by a long riverboat ride and a treacherous hike through dense forest. They are ideal for a number of species that have adapted themselves to live in the dark environment with constant humidity of as much as 100 percent.
